1. Field of the Invention
The present invention relates to detachable attachment structure and electric connection box therewith which is attached to panel or reinforcement of a vehicle, and is effective in recovery of the electric connection box connected to wiring harness, a harness protector, etc.
2. Related Art
A plurality of long members such as wiring harness are arranged in a vehicle. These wiring harness are connected with a junction box as an electric connection box, a connector block, a relay block, an ECU box, etc. attached in the vehicle body panel etc., or protected by a harness protector. For example, as shown in FIG. 6, a junction box 10 attached with a securing bolt (not shown) to one panel side 20a of the vehicle body panel 20 and the junction box 10 attached in another panel side 20b are connected through a wiring harness 25, and this wiring harness 25 is arranged along a reinforcement 21.
At the time of vehicles scrap, a J hook 26 is hooked on the central part of the wiring harness 25 arranged, the J hook 26 is pulled by the crane etc. above the vehicle body panel 20, and the recovery of the junction block 10 is performed.
However, since the junction box 10 is firmly fixed so that it may not fall away by vibration during moving vehicle, when the J hook 26 is pulled, the wiring harness 25 disconnects, or the connector connected to the junction box 10 pulls out, and only the junction box 10 might be left at the vehicle body panel 20.
And when the junction box 10 is left, the securing bolt inserted from attachment brackets 15 and 17 of the junction box 10 is loosened by an impact wrench etc., and the junction box 10 is removed while the worker body is bent. Then the man-hour increases to detach and it causes a problem that the recovering workability becomes worse.
Then, in order to solve this problem, an attachment construction where electric connection boxes such as a junction box fixed to a vehicle body panel etc., are easily recovered is proposed by the applicant (patent reference 1).
The junction box is provided with the case body 54 receiving a fuse, a relay, etc. inside, and an attachment bracket 50 (FIG. 7) disposed to the case main body 54 and fixed to a vehicle body panel. The attachment bracket 50 has a tongue shape, projected and formed at the side of the case main body 54, and is fixed to a vehicle body panel with a securing bolt.
The easy fracture portion 53 formed in the attachment bracket 50 is formed with a cutout 51 and a fracture hole 52 aligned the same line with the cutout 51. The smaller cross section of the easy fracture portion 53 than other portions causes the stress concentration at this portion, and is capable of fracture separation of the case main body 54 and the attachment bracket 50 by small external force.
According to this construction, if an external force acts on the junction box, a crack generates at easy fracture portion 53 of the attachment bracket 50 and progresses along the L line connecting the cutout 51 and a fracture hole 52. It is effective to recover the case main body 54 without damaging the case main body 54.
The following patent documents disclose other conventional examples (patent documents 2-4). The patent document 2 discloses that the case main body is provided with a retractable movable bracket and a urging member to urge the movable bracket, and the movable bracket is disposed at the attachment part of the vehicle body in a stretched state. On recovering the case main body, the wiring harness from the case main body is pulled, the movable bracket is shrunk, and the case main body is detached from the attachment part of the vehicle side.
The patent document 3 discloses that a case main body is provided with an attachment portion having an assembly hole, an auxiliary member having a male screw is screwed together a female screw of the assembly hole and the case main body is attached to the vehicle body. On recovering the case main body, the wiring harness guided out from the case main body is pulled out, the thread of the male screw is deformed, the auxiliary member is detached from the assembly hole, and the case main body is detached from the vehicle body.
Patent document 4 discloses that an attachment portion protruded from the case main body fixed to the vehicle body comprises a flat portion, a screw hole disposed in the center of width direction of the flat portion, and a tube provided perpendicularly along the edge of the screw hole. By adjusting the thickness of the flat portion, the flat portion does not fracture using the vehicle, but fractures on recovering the case main body.    Patent document 1: JP.2000-350331(pages 2-3, FIG. 3)    Patent document 2: JP.2000-4526(pages 2-3)    Patent document 3: JP.2000-78721(pages 2-3)    Patent document 4: JP.2003-189440(pages 2-3)
However, there is a following problem to be solved with the aforementioned conventional attachment structure.
In the 1st conventional example (patent document 1), when contingency external force acts on the easy fracture part 53 by the vibration or shock under vehicles run, there is a possibility that the easy fracture part 53 might fracture carelessly. When the easy fracture part 53 fractures, a junction box may separate from a vehicle body panel and hang in air, then a connector may fall out from a junction box causing a non-conducting state, the wiring harness may be disconnected, or the junction box itself may be collided and damaged on the vehicle body panel. Moreover, since the attachment bracket 50 is fractured, even if the case main body 54 is recovered, it is not reusable.
In the 2nd conventional example (patent document 2), the case main body is not attached with the securing bolt, but secured to a vehicle body side only by a spring force of an urging member. When a movable bracket or the attachment portion of the body side receives contigency external force by the vibration or shock during vehicles run, there is a fear of the case main body detaching from the body side like the 1st conventional example.
In the 3rd conventional example (patent document 3), a case main body can be non-destructively recovered without damaging an attachment portion, but another member, i.e. an auxiliary member, besides the case main body is required and increases the number of parts resulting in the additional time for installing the case main body. Moreover, a female screw is formed at a assembly hole of the attachment portion, and a male screw is formed in an auxiliary member. Then the processing cost becomes higher and the cheap price auto parts can not be provided.
Although the 4th conventional example (patent document 4) offers a attachment structure of simple constitution, it is difficult to set a board thickness of a flat portion as an arbitrary board thickness so that the flat portion may not be fractured at the time of vehicles use but may be fractured at the time of the case main body recovery. In case there is a fear of the flat portion fracturing at the time of vehicles use, or the flat portion not fracturing at the time of the case main body recovery.
In view of the aforementioned points, the present invention aims to provide a detachable attachment structure and an electric junction box thereof which prevent the part main body from falling away improperly from a vehicle body by the vibration or shock of a moving vehicle and are capable of removing the part main body from the vehicle body only at the disassembly of the vehicle resulting in the improvement of the recovery workability and recycling of the part main body.